CA2396019A1 - Led-based planar light source - Google Patents
Led-based planar light source Download PDFInfo
- Publication number
- CA2396019A1 CA2396019A1 CA002396019A CA2396019A CA2396019A1 CA 2396019 A1 CA2396019 A1 CA 2396019A1 CA 002396019 A CA002396019 A CA 002396019A CA 2396019 A CA2396019 A CA 2396019A CA 2396019 A1 CA2396019 A1 CA 2396019A1
- Authority
- CA
- Canada
- Prior art keywords
- light source
- blue
- planar light
- emitting
- source according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 230000005855 radiation Effects 0.000 claims abstract description 28
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 30
- 238000006243 chemical reaction Methods 0.000 claims description 10
- 238000000295 emission spectrum Methods 0.000 claims description 9
- 239000000758 substrate Substances 0.000 claims description 5
- 239000004020 conductor Substances 0.000 claims description 4
- 230000003287 optical effect Effects 0.000 claims description 4
- 238000000862 absorption spectrum Methods 0.000 claims description 2
- 230000003595 spectral effect Effects 0.000 abstract 1
- 238000010521 absorption reaction Methods 0.000 description 11
- 238000001228 spectrum Methods 0.000 description 8
- 239000000203 mixture Substances 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000009877 rendering Methods 0.000 description 2
- 229910052594 sapphire Inorganic materials 0.000 description 2
- 239000010980 sapphire Substances 0.000 description 2
- 229910003668 SrAl Inorganic materials 0.000 description 1
- 239000012190 activator Substances 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 230000000295 complement effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 238000006862 quantum yield reaction Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
- G02F1/133602—Direct backlight
- G02F1/133603—Direct backlight with LEDs
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
- G02F1/133614—Illuminating devices using photoluminescence, e.g. phosphors illuminated by UV or blue light
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L25/00—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof
- H01L25/03—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes
- H01L25/04—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers
- H01L25/075—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00
- H01L25/0753—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00 the devices being arranged next to each other
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/0001—Technical content checked by a classifier
- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
- H01L33/50—Wavelength conversion elements
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S362/00—Illumination
- Y10S362/80—Light emitting diode
Landscapes
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Optics & Photonics (AREA)
- Crystallography & Structural Chemistry (AREA)
- Chemical & Material Sciences (AREA)
- General Physics & Mathematics (AREA)
- Mathematical Physics (AREA)
- Led Device Packages (AREA)
- Luminescent Compositions (AREA)
- Liquid Crystal (AREA)
- Planar Illumination Modules (AREA)
- Led Devices (AREA)
- Illuminated Signs And Luminous Advertising (AREA)
Abstract
The planar light source (1) uses the principle of RGB mixing, the radiation of UV diodes (5) arranged in a planar fashion being converted by means of phosphors (7) which emit in the red and green spectral regions. The blue component is added by blue-emitting LEDs (8) whose radiation is preferably, launched as a lateral diode row (9).
Description
~ CA 02396019 2002-07-29 US-Version/WER
Patent-Treuhand-Gesellschaft fur elektrische Gliihlampen mbH., Munich LED-based planar light source Technical Field The invention relates to an LED-based planar light source in accordance with the preamble of Claim 1. In particular, this is a planar light source for LCD backlighting, or else for other applications, which is, in particular, fully colour-capable and, moreover, has a high luminance.
Background Art JP-A 7-176794 has already disclosed an LED-based planar light source in the case of which a blue LED produces white light on a planar surface by means of partial conversion by a yellow-orange phosphor. However, this simple complementary mixing does not 2 0 permit good colour rendering.
A more complicated concept with better colour rendering is three colour mixing. In this case, the primary colours red-green-blue (RGB) are used to produce white by mixing. Use can be made here either of a blue LED for the partial conversion of two phosphors which emit red and green (WO 00/33390), or of a UV-emitting LED
which excites three phosphors which respectively have their emission in the red, green and blue - see WO 97/48138. Examples are line emitters such as YOB:Ce,Tb (green) and YOS:Eu (red).
However, this requires a relatively shortwave emission (UV region < 370 nm) in order to be able to achieve high quantum yields. This conditions the use of sapphire substrates for the UV-LEDs which are very expensive. On the other hand, if use is made of a UV-LED
based on the cheaper SiC substrates, it is necessary to accept an emission in the region of 380 to 420 nm, and this renders difficult or impossible the use of line emitters in the green and red. This leads to absorption problems in the case of blue phosphors.
' ~ ' ~ CA 02396019 2002-07-29 _ A specific problem here is, moreover, the additional absorption loss of blue radiation owing to the broadband nature of the absorption of the red- and green-emitting phosphors. Taken altogether, this leads to clear restrictions in the setting of the light colour and/or the luminance efficiency.
Disclosure of the Invention It is an object of the present invention to provide a fully colour-capable planar light source utilizing the colour mixing principle, the radiation from UV-emitting diodes arranged in a planar fashion being converted into light of longer wavelength by means of conversion by at least one UV-absorbing phosphor, and this light being mixed with a blue component, which achieves a 1 5 high luminance efficiency and yet is economical.
This object is achieved by means of the following features: the radiation of the UV diodes is absorbed by the at least one phosphor while the blue component is provided by at least one 2 0 blue-emitting LED.
Particularly advantageous refinements are to be found in the dependent claims.
2 5 Planar light sources as described in outline in US-A 5 619 351, for example, are frequently used for backlighting of LCDs. In this case, a compact fluorescent lamp has predominantly been used to date as light source. This requires a high supply voltage and creates problems with electromagnetic compatibility, for which 3 0 reason it is worth attempting to replace the lamps by LEDs.
According to the invention, a planar light source which is fully colour-capable is provided by utilizing the RGB principle, the radiation of a multiplicity of UV diodes arranged in a planar 3 5 fashion being converted into light of longer wavelength by means of conversion by phosphors. Here, the term UV means the region of 300 to 920 nm. The radiation of the UV diodes is absorbed solely by green-emitting phosphors (preferably with a peak emission wavelength between 510 and 560 nm, for example SrAl~O,~: Eu'' or Eu''-~ ~ CA 02396019 2002-07-29 based thiogallates) and red-emitting phosphors (preferably with a peak emission wavelength of more than 590 nm up to 690 nm, for example Sr2Si5N8:Eu2') while the blue component (preferably with a peak emission wavelength between 430 and 490 nm) is provided by blue-emitting LEDs. This principle is surprising per se, because at first glance it appears substantially more complicated than the known solutions, since more LEDs are used, and the latter must be driven in a fashion separated at least into two groups (UV-LEDs and blue LEDs).
However, it is to be borne in mind in this case that the price of blue LEDs is more favourable than the price of UV-LEDs, and that, on the other hand, it is possible to economize on a few UV-LEDs .
Moreover, a spatial separation of the blue LEDs from the red and green phosphors provides an elegant possibility of avoiding partial absorption of the blue radiation of the LEDs by these RG
phosphors. Consequently, a more efficient light source can be created at lower cost. Finally, particular advantages are associated with the fact that instead of an expensive UV-LED on a 2 0 sapphire substrate with an emission peak below 380 nm it is possible to use as UV-LED a cheap GaN-based LED (preferably doped with In and/or A1) on an SiC substrate with an emission peak between 380 and 420 nm. The point is that a slight overlap between the emission spectrum of the UV-LED and an absorption spectrum of, 2 5 for example, a blue-emitting phosphor plays no role at all in the concept according to the invention, while it yields poorer results in the case of the conversion of UV into blue (> 380 nm). This energy spacing (overlap) between excitation source and absorption curve of the phosphor no longer plays an important role with 30 reference to the red- or green-emitting phosphor which, in some circumstances, both use the same activator, in particular Eu. In general, it emerges that the absorption problem no longer plays a role in the case of broadband-emitting phosphors, in particular starting from approximately 490 nm peak emission. The concept of 35 the present invention can therefore not only be applied in the case of RGB mixtures, but also includes the application of additional phosphors. A further application is, finally, the production of a white light source on the simpler principle of blue-yellow mixing, in accordance with the first white-emitting ~ ~ CA 02396019 2002-07-29 LEDs of the prior art. In this case, the blue component is provided here by the primary emission of a number of blue LEDs, and the yellow component is provided by the yellow emission of a suitable phosphor excited by a number of UV-LEDs. A further application is, moreover, the provision of a planar light source of specific colour, it being possible for this special colour to be produced by mixing a blue and a further component. In this case, the blue component is again provided by the primary emission of a number of blue LEDs, and the further components are provided by the emission of a (or else a plurality of further) suitable phosphor excited by a number of UV-LEDs, the desired colour resulting from the mixing of the emissions. Concrete examples for such phosphors have, for example, peak emissions in the blue-green (for example Sr6BP50~o:Euz', Sr4A1140~5:EU'') or green-yellow or yellow ( for example Sr~SiSNa: Ce", (Sr, Ba) Si04: Eu'+) or yellow-orange ( for example Ca~Si~,N,3:EU'', Cal~SAl,,Si~N1'':Eu'') .
In principle, the RG phosphors can be placed directly on the individual UV-LEDs. It is advantageous for the red- and green-2 0 emitting phosphors to be applied to, or implemented inside, on an optical conductor fitted at a spacing from the UV diodes, or on a transparent plate acting like an optical conductor, because the spacing yields a better uniformity of the planar emission. The number of the blue-emitting LEDs per assembly is at most equal to 2 5 the number of the UV diodes. In the case when the blue-emitting LEDs are arranged in a planar fashion, it corresponds approximately to the number of the UV diodes (50 to 100, correspondingly).
30 A substantial reduction in the number of the blue-emitting LEDs (typically by 10 to 40~) can be achieved when the blue-emitting LEDs are arranged in rows at the edge of the surface fitted with the UV-LEDs. They are then launched into the forward emission of the surface by means of suitable techniques known per se. In the 35 simplest case, a single row is arranged laterally at an edge strip next to an array of UV diodes. It is typical in this case for the launching to be achieved by means of a wedge-shaped (or else flat) plate which has punctiform etchings of different density such that a uniform brightness of the surface is achieved overall.
~ ' CA 02396019 2002-07-29 However, this technique can be modified to the effect that a plurality of edge strips with LEDs arranged in rows are fitted. In the simplest case, therefore, two rows are arranged laterally next to edges of a surface of UV diodes. Proceeding from a rectangular surface, the two rows can be at a right angle to one another or be arranged parallel to one another at opposite edges.
Brief Description of the Drawings The invention is to be explained in more detail below with the aid of a plurality of exemplary embodiments. In the drawing:
Figure 1 shows a planar light source, in section;
Figure 2 shows an emission and reflection spectrum of a green-emitting phosphor:
Figure 3 shows an emission and reflection spectrum of a red-emitting phosphor;
Figure 4 shows an emission spectrum of a lighting unit according 2 0 to the invention, compared with a conventional lighting unit; and Figure 5 shows an emission spectrum of a lighting unit according to the invention, with and without a dedicated blue component.
Best Mode for Carrying Out the Invention Figure 1 shows an LCD display device 1 with a planar light source 2 for backlighting an LCD display 3. An additionally present 3 0 rectangular housing has been omitted for the sake of simplicity, as is true of customary additional components such as polarization and colour filters and drive units (for example TFTs). The planar light source 2 comprises a basic body 4 on which an array of UV
diodes 5 are arranged spaced apart uniformly in the shape of a 3 5 raster. An optical conductor plate 6, which can be wedge-shaped (no wedge shape is shown) , is spaced apart in front of the basic body 4 and mounted parallel thereto. The plate 6 has output means for the uniform upward emission of laterally irradiated light. In the case of a wedge-shaped plate, these coupling centres can be distributed uniformly on the surface of the plate. In the case of a plane-parallel plate, the arrangement of the centres is nonuniform, since only so is it possible for the blue light to be emitted in a fashion distributed uniformly over the surface of the plate. On the side facing the UV-LEDs, the plate 6 is provided with a coating 7 which comprises a mixture of two phosphors with green and red emission. The UV radiation of the diodes 5 (InGaN
with 390 nm peak emission wavelength) is converted here virtually completely into red and green light.
Fitted laterally at an edge of the transparent plate 6 (made from glass, plastic, PET or the like) is a row of blue-emitting LEDs 8 whose light is emitted into the plate 6 and is output forwards by the coupling centres 10 on the surface of the plate 6 (for example 1 5 etchings on the front side of the plate or microprisms, or the like). The blue light mixes with the green and red light from the coating 7 to form white.
The two types of LEDs 5, 8 are driven separately (not illustrated) 2 0 and can thereby be set to a desired colour location, or else corrected.
To provide a better understanding of the mode of operation and of the advantages, Figure 2 shows the emission spectrum and 2 5 reflection spectrum of an advantageously employed green-emitting phosphor SrAlzO~:Euz' with emission peak wavelength at 524 nm. At the same time, the reflection spectrum also shows the absorption behaviour in accordance with the known relationship R(~) - 100 -A (~) where R = reflection and A = absorption. Furthermore, the 3 0 emission spectrum of a blue-emitting phosphor (BaMgAl1~01i:Eu, known as BAM) typically used in the prior art is illustrated in the reflection spectrum. It may clearly be seen here that the blue radiation of the BAM would be largely absorbed by the green phosphor. This problem is completely avoided by means of the 3 5 concept of the present invention.
Similarly, Figure 3 shows the emission spectrum and reflection spectrum of an advantageously employed red-emitting phosphor Sr~Si~,N~:Eu2' with emission peak wavelength at 623 nrn. Here, as ' CA 02396019 2002-07-29 _ 7 _ well, a blue-emitting phosphor (BAM) typically used in the prior art is illustrated in the reflection spectrum. In this case, as well, a partial absorption of the blue radiation by the red phosphor would be active.
Figure 4 shows the emission spectrum of an inventive planar light source with a UV diode array, the conversion of the UV radiation by a previously known phosphor mixture of RGB phosphors as described above being illustrated (1) for the purposes of comparison. According to the invention, a row of blue-emitting LEDs is used (2) instead of the blue phosphor. This arrangement shows a rise in efficiency by 30~ (because absorbing mechanisms are eliminated), 10~ of the number of the UV-LEDs (originally 50) being dispensed with. Use is made, instead, of a row of blue LEDs (10 items).
Figure 5 shows the emission spectrum of an inventive planar light source with a UV diode array (peak wavelength 905 m), the conversion of the UV radiation by a previously known phosphor 2 0 mixture of RG phosphors as described above being illustrated (1) for the purposes of comparison. According to the invention, a row of blue-emitting LEDs (peak wavelength 960 m) is coupled in (2).
This arrangement is set up such that the resulting spectrum is in the vicinity of the white point. For this purpose, the proportion 2 5 of the blue radiation must be substantially greater compared to the green and red proportions, in order to take account of the sensitivity of the human eye, which is lower in the blue.
A particularly advantageous utilization of the novel mixing 30 principle consists in making an entirely conscious selection as far as possible of a red phosphor and also of a green phosphor which absorbs in each case at least a portion of the blue primary radiation (LED). At least one of the phosphors advantageously absorbs the blue primary radiation as completely as possible.
35 Absorption of the blue radiation is avoided nevertheless owing to the fact that the admixture of the blue radiation in the beam path is performed only after the conversion. A portion of the blue radiation which is deflected in the forward direction is, however, backscattered at the boundary surfaces, consequently traverses the ~
phosphor layer and is converted there at least partially and partially re-emitted in the forward direction. This actually lost portion of the blue radiation is therefore added to the useful radiation, whereas without the possibility of absorption by the red phosphor, and also to a lesser extent by the green phosphor, it could not be used and would, rather, lead to heating up the light source undesirably.
The same concept can also, of course, be implemented in the case of a yellow phosphor.
Patent-Treuhand-Gesellschaft fur elektrische Gliihlampen mbH., Munich LED-based planar light source Technical Field The invention relates to an LED-based planar light source in accordance with the preamble of Claim 1. In particular, this is a planar light source for LCD backlighting, or else for other applications, which is, in particular, fully colour-capable and, moreover, has a high luminance.
Background Art JP-A 7-176794 has already disclosed an LED-based planar light source in the case of which a blue LED produces white light on a planar surface by means of partial conversion by a yellow-orange phosphor. However, this simple complementary mixing does not 2 0 permit good colour rendering.
A more complicated concept with better colour rendering is three colour mixing. In this case, the primary colours red-green-blue (RGB) are used to produce white by mixing. Use can be made here either of a blue LED for the partial conversion of two phosphors which emit red and green (WO 00/33390), or of a UV-emitting LED
which excites three phosphors which respectively have their emission in the red, green and blue - see WO 97/48138. Examples are line emitters such as YOB:Ce,Tb (green) and YOS:Eu (red).
However, this requires a relatively shortwave emission (UV region < 370 nm) in order to be able to achieve high quantum yields. This conditions the use of sapphire substrates for the UV-LEDs which are very expensive. On the other hand, if use is made of a UV-LED
based on the cheaper SiC substrates, it is necessary to accept an emission in the region of 380 to 420 nm, and this renders difficult or impossible the use of line emitters in the green and red. This leads to absorption problems in the case of blue phosphors.
' ~ ' ~ CA 02396019 2002-07-29 _ A specific problem here is, moreover, the additional absorption loss of blue radiation owing to the broadband nature of the absorption of the red- and green-emitting phosphors. Taken altogether, this leads to clear restrictions in the setting of the light colour and/or the luminance efficiency.
Disclosure of the Invention It is an object of the present invention to provide a fully colour-capable planar light source utilizing the colour mixing principle, the radiation from UV-emitting diodes arranged in a planar fashion being converted into light of longer wavelength by means of conversion by at least one UV-absorbing phosphor, and this light being mixed with a blue component, which achieves a 1 5 high luminance efficiency and yet is economical.
This object is achieved by means of the following features: the radiation of the UV diodes is absorbed by the at least one phosphor while the blue component is provided by at least one 2 0 blue-emitting LED.
Particularly advantageous refinements are to be found in the dependent claims.
2 5 Planar light sources as described in outline in US-A 5 619 351, for example, are frequently used for backlighting of LCDs. In this case, a compact fluorescent lamp has predominantly been used to date as light source. This requires a high supply voltage and creates problems with electromagnetic compatibility, for which 3 0 reason it is worth attempting to replace the lamps by LEDs.
According to the invention, a planar light source which is fully colour-capable is provided by utilizing the RGB principle, the radiation of a multiplicity of UV diodes arranged in a planar 3 5 fashion being converted into light of longer wavelength by means of conversion by phosphors. Here, the term UV means the region of 300 to 920 nm. The radiation of the UV diodes is absorbed solely by green-emitting phosphors (preferably with a peak emission wavelength between 510 and 560 nm, for example SrAl~O,~: Eu'' or Eu''-~ ~ CA 02396019 2002-07-29 based thiogallates) and red-emitting phosphors (preferably with a peak emission wavelength of more than 590 nm up to 690 nm, for example Sr2Si5N8:Eu2') while the blue component (preferably with a peak emission wavelength between 430 and 490 nm) is provided by blue-emitting LEDs. This principle is surprising per se, because at first glance it appears substantially more complicated than the known solutions, since more LEDs are used, and the latter must be driven in a fashion separated at least into two groups (UV-LEDs and blue LEDs).
However, it is to be borne in mind in this case that the price of blue LEDs is more favourable than the price of UV-LEDs, and that, on the other hand, it is possible to economize on a few UV-LEDs .
Moreover, a spatial separation of the blue LEDs from the red and green phosphors provides an elegant possibility of avoiding partial absorption of the blue radiation of the LEDs by these RG
phosphors. Consequently, a more efficient light source can be created at lower cost. Finally, particular advantages are associated with the fact that instead of an expensive UV-LED on a 2 0 sapphire substrate with an emission peak below 380 nm it is possible to use as UV-LED a cheap GaN-based LED (preferably doped with In and/or A1) on an SiC substrate with an emission peak between 380 and 420 nm. The point is that a slight overlap between the emission spectrum of the UV-LED and an absorption spectrum of, 2 5 for example, a blue-emitting phosphor plays no role at all in the concept according to the invention, while it yields poorer results in the case of the conversion of UV into blue (> 380 nm). This energy spacing (overlap) between excitation source and absorption curve of the phosphor no longer plays an important role with 30 reference to the red- or green-emitting phosphor which, in some circumstances, both use the same activator, in particular Eu. In general, it emerges that the absorption problem no longer plays a role in the case of broadband-emitting phosphors, in particular starting from approximately 490 nm peak emission. The concept of 35 the present invention can therefore not only be applied in the case of RGB mixtures, but also includes the application of additional phosphors. A further application is, finally, the production of a white light source on the simpler principle of blue-yellow mixing, in accordance with the first white-emitting ~ ~ CA 02396019 2002-07-29 LEDs of the prior art. In this case, the blue component is provided here by the primary emission of a number of blue LEDs, and the yellow component is provided by the yellow emission of a suitable phosphor excited by a number of UV-LEDs. A further application is, moreover, the provision of a planar light source of specific colour, it being possible for this special colour to be produced by mixing a blue and a further component. In this case, the blue component is again provided by the primary emission of a number of blue LEDs, and the further components are provided by the emission of a (or else a plurality of further) suitable phosphor excited by a number of UV-LEDs, the desired colour resulting from the mixing of the emissions. Concrete examples for such phosphors have, for example, peak emissions in the blue-green (for example Sr6BP50~o:Euz', Sr4A1140~5:EU'') or green-yellow or yellow ( for example Sr~SiSNa: Ce", (Sr, Ba) Si04: Eu'+) or yellow-orange ( for example Ca~Si~,N,3:EU'', Cal~SAl,,Si~N1'':Eu'') .
In principle, the RG phosphors can be placed directly on the individual UV-LEDs. It is advantageous for the red- and green-2 0 emitting phosphors to be applied to, or implemented inside, on an optical conductor fitted at a spacing from the UV diodes, or on a transparent plate acting like an optical conductor, because the spacing yields a better uniformity of the planar emission. The number of the blue-emitting LEDs per assembly is at most equal to 2 5 the number of the UV diodes. In the case when the blue-emitting LEDs are arranged in a planar fashion, it corresponds approximately to the number of the UV diodes (50 to 100, correspondingly).
30 A substantial reduction in the number of the blue-emitting LEDs (typically by 10 to 40~) can be achieved when the blue-emitting LEDs are arranged in rows at the edge of the surface fitted with the UV-LEDs. They are then launched into the forward emission of the surface by means of suitable techniques known per se. In the 35 simplest case, a single row is arranged laterally at an edge strip next to an array of UV diodes. It is typical in this case for the launching to be achieved by means of a wedge-shaped (or else flat) plate which has punctiform etchings of different density such that a uniform brightness of the surface is achieved overall.
~ ' CA 02396019 2002-07-29 However, this technique can be modified to the effect that a plurality of edge strips with LEDs arranged in rows are fitted. In the simplest case, therefore, two rows are arranged laterally next to edges of a surface of UV diodes. Proceeding from a rectangular surface, the two rows can be at a right angle to one another or be arranged parallel to one another at opposite edges.
Brief Description of the Drawings The invention is to be explained in more detail below with the aid of a plurality of exemplary embodiments. In the drawing:
Figure 1 shows a planar light source, in section;
Figure 2 shows an emission and reflection spectrum of a green-emitting phosphor:
Figure 3 shows an emission and reflection spectrum of a red-emitting phosphor;
Figure 4 shows an emission spectrum of a lighting unit according 2 0 to the invention, compared with a conventional lighting unit; and Figure 5 shows an emission spectrum of a lighting unit according to the invention, with and without a dedicated blue component.
Best Mode for Carrying Out the Invention Figure 1 shows an LCD display device 1 with a planar light source 2 for backlighting an LCD display 3. An additionally present 3 0 rectangular housing has been omitted for the sake of simplicity, as is true of customary additional components such as polarization and colour filters and drive units (for example TFTs). The planar light source 2 comprises a basic body 4 on which an array of UV
diodes 5 are arranged spaced apart uniformly in the shape of a 3 5 raster. An optical conductor plate 6, which can be wedge-shaped (no wedge shape is shown) , is spaced apart in front of the basic body 4 and mounted parallel thereto. The plate 6 has output means for the uniform upward emission of laterally irradiated light. In the case of a wedge-shaped plate, these coupling centres can be distributed uniformly on the surface of the plate. In the case of a plane-parallel plate, the arrangement of the centres is nonuniform, since only so is it possible for the blue light to be emitted in a fashion distributed uniformly over the surface of the plate. On the side facing the UV-LEDs, the plate 6 is provided with a coating 7 which comprises a mixture of two phosphors with green and red emission. The UV radiation of the diodes 5 (InGaN
with 390 nm peak emission wavelength) is converted here virtually completely into red and green light.
Fitted laterally at an edge of the transparent plate 6 (made from glass, plastic, PET or the like) is a row of blue-emitting LEDs 8 whose light is emitted into the plate 6 and is output forwards by the coupling centres 10 on the surface of the plate 6 (for example 1 5 etchings on the front side of the plate or microprisms, or the like). The blue light mixes with the green and red light from the coating 7 to form white.
The two types of LEDs 5, 8 are driven separately (not illustrated) 2 0 and can thereby be set to a desired colour location, or else corrected.
To provide a better understanding of the mode of operation and of the advantages, Figure 2 shows the emission spectrum and 2 5 reflection spectrum of an advantageously employed green-emitting phosphor SrAlzO~:Euz' with emission peak wavelength at 524 nm. At the same time, the reflection spectrum also shows the absorption behaviour in accordance with the known relationship R(~) - 100 -A (~) where R = reflection and A = absorption. Furthermore, the 3 0 emission spectrum of a blue-emitting phosphor (BaMgAl1~01i:Eu, known as BAM) typically used in the prior art is illustrated in the reflection spectrum. It may clearly be seen here that the blue radiation of the BAM would be largely absorbed by the green phosphor. This problem is completely avoided by means of the 3 5 concept of the present invention.
Similarly, Figure 3 shows the emission spectrum and reflection spectrum of an advantageously employed red-emitting phosphor Sr~Si~,N~:Eu2' with emission peak wavelength at 623 nrn. Here, as ' CA 02396019 2002-07-29 _ 7 _ well, a blue-emitting phosphor (BAM) typically used in the prior art is illustrated in the reflection spectrum. In this case, as well, a partial absorption of the blue radiation by the red phosphor would be active.
Figure 4 shows the emission spectrum of an inventive planar light source with a UV diode array, the conversion of the UV radiation by a previously known phosphor mixture of RGB phosphors as described above being illustrated (1) for the purposes of comparison. According to the invention, a row of blue-emitting LEDs is used (2) instead of the blue phosphor. This arrangement shows a rise in efficiency by 30~ (because absorbing mechanisms are eliminated), 10~ of the number of the UV-LEDs (originally 50) being dispensed with. Use is made, instead, of a row of blue LEDs (10 items).
Figure 5 shows the emission spectrum of an inventive planar light source with a UV diode array (peak wavelength 905 m), the conversion of the UV radiation by a previously known phosphor 2 0 mixture of RG phosphors as described above being illustrated (1) for the purposes of comparison. According to the invention, a row of blue-emitting LEDs (peak wavelength 960 m) is coupled in (2).
This arrangement is set up such that the resulting spectrum is in the vicinity of the white point. For this purpose, the proportion 2 5 of the blue radiation must be substantially greater compared to the green and red proportions, in order to take account of the sensitivity of the human eye, which is lower in the blue.
A particularly advantageous utilization of the novel mixing 30 principle consists in making an entirely conscious selection as far as possible of a red phosphor and also of a green phosphor which absorbs in each case at least a portion of the blue primary radiation (LED). At least one of the phosphors advantageously absorbs the blue primary radiation as completely as possible.
35 Absorption of the blue radiation is avoided nevertheless owing to the fact that the admixture of the blue radiation in the beam path is performed only after the conversion. A portion of the blue radiation which is deflected in the forward direction is, however, backscattered at the boundary surfaces, consequently traverses the ~
phosphor layer and is converted there at least partially and partially re-emitted in the forward direction. This actually lost portion of the blue radiation is therefore added to the useful radiation, whereas without the possibility of absorption by the red phosphor, and also to a lesser extent by the green phosphor, it could not be used and would, rather, lead to heating up the light source undesirably.
The same concept can also, of course, be implemented in the case of a yellow phosphor.
Claims (14)
1. LED-based planar light source utilizing the colour mixing principle, the radiation from UV-emitting diodes arranged in a planar fashion being converted into light of longer wavelength by means of conversion by at least one UV-absorbing phosphor, and this light being mixed with a blue component, wherein the radiation of the UV diodes is absorbed by the at least one phosphor while the blue component is provided by at least one blue-emitting LED.
2. Planar light source according to Claim 1, wherein the radiation of the UV diodes is absorbed by red- and green-emitting phosphors in order to provide a white-emitting light source by utilizing the RGB principle.
3. Planar light source according to Claim 1, wherein the radiation of the UV diodes is absorbed by a yellow-emitting phosphor in order to provide a white-emitting light source by utilizing the blue-yellow mixing principle.
4. Planar light source according to Claim 1, wherein the radiation of the UV diodes is absorbed by one or a plurality of colour-emitting phosphors in order to provide a colour-emitting light source by utilizing the colour mixing principle.
5. Planar light source according to Claim 1, wherein the UV-absorbing phosphors are applied to an optical conductor fitted at a spacing from the UV diodes, or to a transparent plate.
6. Planar light source according to Claim 1, characterized in that the number of the blue-emitting LEDs is at most equal to the number of the UV diodes.
7. Planar light source according to Claim 1, wherein the blue-emitting LEDs are arranged in a planar fashion.
8. Planar light source according to Claim 1, wherein the blue-emitting LEDs are arranged in rows.
9. Planar light source according to Claim 8, wherein a row of blue-emitting LEDs is arranged next to an array of UV diodes.
10. Planar light source according to Claim 8, wherein at least two rows of blue-emitting LEDs are arranged next to edges of a surface of UV diodes.
11. Planar light source according to Claim 1, wherein an GaN-based LED on an SiC substrate is used as UV diode.
12. Planar light source according to Claim 1, wherein the peak wavelength of the primary UV emission is at 300 to 420 nm, and the peak wavelength of the blue emission is at 430 to 490 nm, and the secondary emission of green and red phosphors has a peak wavelength of 510 to 560 or 590 to 680 nm.
13. Planar light source according to Claim 1, wherein the admixture of the blue component of the radiation is performed only after the conversion of the UV radiation.
14. Planar light source according to Claim 1, wherein the absorption spectrum at least of the red phosphor overlaps at least partially with the emission spectrum of the blue LEDs.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE10137042A DE10137042A1 (en) | 2001-07-31 | 2001-07-31 | Planar light source based on LED |
| DE10137042.3 | 2001-07-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2396019A1 true CA2396019A1 (en) | 2003-01-31 |
Family
ID=7693562
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002396019A Abandoned CA2396019A1 (en) | 2001-07-31 | 2002-07-29 | Led-based planar light source |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US6799865B2 (en) |
| EP (1) | EP1282171B1 (en) |
| JP (1) | JP4035394B2 (en) |
| AT (1) | ATE513313T1 (en) |
| CA (1) | CA2396019A1 (en) |
| DE (1) | DE10137042A1 (en) |
Families Citing this family (97)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005530349A (en) * | 2002-06-13 | 2005-10-06 | クリー インコーポレイテッド | Emitter package with saturation conversion material |
| DE10245892A1 (en) * | 2002-09-30 | 2004-05-13 | Siemens Ag | Illumination device for backlighting an image display device |
| US7063449B2 (en) * | 2002-11-21 | 2006-06-20 | Element Labs, Inc. | Light emitting diode (LED) picture element |
| US7005679B2 (en) | 2003-05-01 | 2006-02-28 | Cree, Inc. | Multiple component solid state white light |
| EP1627179B1 (en) * | 2003-05-05 | 2008-10-08 | Lumination LLC | Method and apparatus for led panel lamp systems |
| EP1670875B1 (en) | 2003-09-24 | 2019-08-14 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | Highly efficient led-based illumination system featuring improved color rendering |
| US7052152B2 (en) * | 2003-10-03 | 2006-05-30 | Philips Lumileds Lighting Company, Llc | LCD backlight using two-dimensional array LEDs |
| US7250715B2 (en) * | 2004-02-23 | 2007-07-31 | Philips Lumileds Lighting Company, Llc | Wavelength converted semiconductor light emitting devices |
| DE102004015700A1 (en) * | 2004-03-29 | 2005-11-03 | Platsch Gmbh & Co.Kg | Flat UV light source |
| CA2565339C (en) | 2004-05-05 | 2012-11-06 | Rensselaer Polytechnic Institute | High efficiency light source using solid-state emitter and down-conversion material |
| US7837348B2 (en) | 2004-05-05 | 2010-11-23 | Rensselaer Polytechnic Institute | Lighting system using multiple colored light emitting sources and diffuser element |
| KR100655894B1 (en) * | 2004-05-06 | 2006-12-08 | 서울옵토디바이스주식회사 | Light Emitting Device |
| JP2005321727A (en) * | 2004-05-11 | 2005-11-17 | Sony Corp | Backlight device and color liquid crystal display |
| KR100658700B1 (en) | 2004-05-13 | 2006-12-15 | 서울옵토디바이스주식회사 | Light emitting device with RGB diodes and phosphor converter |
| JP3821141B2 (en) * | 2004-06-14 | 2006-09-13 | ソニー株式会社 | Backlight device and liquid crystal display device |
| US7808585B2 (en) * | 2004-07-15 | 2010-10-05 | Sony Corporation | Color filter and color LCD apparatus having red filter with a peak wavelength between 685 nm and 690 nm and a red light source having a peak wavelength of between 640 nm and 645 nm |
| US7575697B2 (en) * | 2004-08-04 | 2009-08-18 | Intematix Corporation | Silicate-based green phosphors |
| JP4813484B2 (en) * | 2004-08-06 | 2011-11-09 | コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ | High performance LED lamp system |
| JP4677746B2 (en) * | 2004-08-18 | 2011-04-27 | ソニー株式会社 | Backlight device |
| CN100412649C (en) * | 2004-08-27 | 2008-08-20 | 孙庆成 | Straight down type back light module |
| JP5081370B2 (en) * | 2004-08-31 | 2012-11-28 | 日亜化学工業株式会社 | Light emitting device |
| US8049861B2 (en) * | 2004-10-19 | 2011-11-01 | Sharp Kabushiki Kaisha | Liquid crystal display device and electronic device using the same |
| JP4815781B2 (en) * | 2004-10-20 | 2011-11-16 | ソニー株式会社 | Color liquid crystal display device and backlight device |
| US8026532B2 (en) * | 2004-12-06 | 2011-09-27 | Koninklijke Philips Electronics N.V. | Single chip LED as compact color variable light source |
| US7559664B1 (en) * | 2004-12-27 | 2009-07-14 | John V. Walleman | Low profile backlighting using LEDs |
| US7564180B2 (en) | 2005-01-10 | 2009-07-21 | Cree, Inc. | Light emission device and method utilizing multiple emitters and multiple phosphors |
| US8125137B2 (en) | 2005-01-10 | 2012-02-28 | Cree, Inc. | Multi-chip light emitting device lamps for providing high-CRI warm white light and light fixtures including the same |
| US20100044697A2 (en) * | 2005-04-14 | 2010-02-25 | Duke University | Bright visible wavelength luminescent nanostructures and methods of making and devices for using the same |
| TWI260799B (en) * | 2005-05-06 | 2006-08-21 | Harvatek Corp | Multi-wavelength white light light-emitting diode |
| KR101266130B1 (en) | 2005-06-23 | 2013-05-27 | 렌슬러 폴리테크닉 인스티튜트 | Package design for producing white light with short-wavelength leds and down-conversion materials |
| KR101171182B1 (en) * | 2005-08-05 | 2012-08-06 | 삼성전자주식회사 | Back light unit and liquid crystal display using the same |
| CN100422817C (en) * | 2005-08-19 | 2008-10-01 | 深圳帝光电子有限公司 | Full run-down type back light source |
| JP5614766B2 (en) * | 2005-12-21 | 2014-10-29 | クリー インコーポレイテッドＣｒｅｅ Ｉｎｃ． | Lighting device |
| JP5137847B2 (en) | 2005-12-21 | 2013-02-06 | クリー インコーポレイテッド | Lighting device and lighting method |
| JP2009527071A (en) * | 2005-12-22 | 2009-07-23 | クリー エル イー ディー ライティング ソリューションズ インコーポレイテッド | Lighting device |
| CN101379341B (en) * | 2006-01-31 | 2012-03-21 | 皇家飞利浦电子股份有限公司 | White light source |
| US8174032B2 (en) * | 2006-03-16 | 2012-05-08 | Light Engines Corporation | Semiconductor white light sources |
| KR100875443B1 (en) | 2006-03-31 | 2008-12-23 | 서울반도체 주식회사 | Light emitting device |
| DE102006049081B4 (en) * | 2006-10-13 | 2012-06-14 | Noctron Soparfi S.A. | Semiconductor lamps and light panels with such |
| DE102006015606A1 (en) * | 2006-04-04 | 2007-10-18 | Noctron Holding S.A. | Semiconductor lamps and light panels with such |
| US9084328B2 (en) * | 2006-12-01 | 2015-07-14 | Cree, Inc. | Lighting device and lighting method |
| US8513875B2 (en) | 2006-04-18 | 2013-08-20 | Cree, Inc. | Lighting device and lighting method |
| US7828460B2 (en) * | 2006-04-18 | 2010-11-09 | Cree, Inc. | Lighting device and lighting method |
| KR101517244B1 (en) | 2006-04-20 | 2015-05-04 | 크리, 인코포레이티드 | Lighting device and lighting method |
| KR20070112312A (en) * | 2006-05-20 | 2007-11-23 | 삼성전자주식회사 | Back light assembly and liquid crystal display apparatus having the same |
| CN101589268A (en) | 2006-05-31 | 2009-11-25 | 科锐Led照明科技公司 | Lighting device and method of lighting |
| US7703942B2 (en) | 2006-08-31 | 2010-04-27 | Rensselaer Polytechnic Institute | High-efficient light engines using light emitting diodes |
| JP2008076899A (en) * | 2006-09-22 | 2008-04-03 | Sony Corp | Backlight device and display device |
| KR20090082449A (en) * | 2006-10-31 | 2009-07-30 | 티아이알 테크놀로지 엘피 | Light source comprising a light-excitable medium |
| US8029155B2 (en) * | 2006-11-07 | 2011-10-04 | Cree, Inc. | Lighting device and lighting method |
| US7889421B2 (en) | 2006-11-17 | 2011-02-15 | Rensselaer Polytechnic Institute | High-power white LEDs and manufacturing method thereof |
| JP4285532B2 (en) * | 2006-12-01 | 2009-06-24 | ソニー株式会社 | Backlight control device, backlight control method, and liquid crystal display device |
| US9441793B2 (en) | 2006-12-01 | 2016-09-13 | Cree, Inc. | High efficiency lighting device including one or more solid state light emitters, and method of lighting |
| EP2089654B1 (en) | 2006-12-07 | 2016-08-03 | Cree, Inc. | Lighting device and lighting method |
| JP4264560B2 (en) * | 2007-01-24 | 2009-05-20 | ソニー株式会社 | Backlight device, backlight control method, and liquid crystal display device |
| WO2008103876A1 (en) * | 2007-02-22 | 2008-08-28 | Cree Led Lighting Solutions, Inc. | Lighting devices, methods of lighting, light filters and methods of filtering light |
| JP4536077B2 (en) * | 2007-03-01 | 2010-09-01 | 株式会社沖データ | LED backlight device and liquid crystal display device |
| JP2008218691A (en) * | 2007-03-05 | 2008-09-18 | Oki Data Corp | Led backlight device and liquid crystal display device |
| WO2008126038A1 (en) * | 2007-04-17 | 2008-10-23 | Koninklijke Philips Electronics N.V. | Illumination system |
| TWI489648B (en) | 2007-05-08 | 2015-06-21 | Cree Inc | Lighting device and lighting method |
| JP2010527157A (en) | 2007-05-08 | 2010-08-05 | クリー エル イー ディー ライティング ソリューションズ インコーポレイテッド | Lighting device and lighting method |
| CN101755164B (en) * | 2007-05-08 | 2013-03-27 | 科锐公司 | Lighting device and lighting method |
| CN101711326B (en) | 2007-05-08 | 2012-12-05 | 科锐公司 | Lighting device and lighting method |
| CN101711325B (en) * | 2007-05-08 | 2013-07-10 | 科锐公司 | Lighting device and lighting method |
| US20090039375A1 (en) * | 2007-08-07 | 2009-02-12 | Cree, Inc. | Semiconductor light emitting devices with separated wavelength conversion materials and methods of forming the same |
| US7863635B2 (en) * | 2007-08-07 | 2011-01-04 | Cree, Inc. | Semiconductor light emitting devices with applied wavelength conversion materials |
| CN101784636B (en) | 2007-08-22 | 2013-06-12 | 首尔半导体株式会社 | Non stoichiometric tetragonal copper alkaline earth silicate phosphors and method of preparing the same |
| US20090065715A1 (en) * | 2007-08-24 | 2009-03-12 | Lee Wainright | Universal ultraviolet/ IR/ visible light emitting module |
| KR101055769B1 (en) | 2007-08-28 | 2011-08-11 | 서울반도체 주식회사 | Light-emitting device adopting non-stoichiometric tetra-alkaline earth silicate phosphor |
| JP4381439B2 (en) * | 2007-09-18 | 2009-12-09 | 株式会社沖データ | LED backlight device and liquid crystal display device |
| US8018135B2 (en) * | 2007-10-10 | 2011-09-13 | Cree, Inc. | Lighting device and method of making |
| JP2011501466A (en) * | 2007-10-26 | 2011-01-06 | クリー エル イー ディー ライティング ソリューションズ インコーポレイテッド | Lighting device having one or more light emitters and method of making the same |
| CN101430066A (en) * | 2007-11-06 | 2009-05-13 | 富士迈半导体精密工业（上海）有限公司 | Semiconductor solid state light source module and semiconductor solid state light source module group |
| US8240875B2 (en) | 2008-06-25 | 2012-08-14 | Cree, Inc. | Solid state linear array modules for general illumination |
| US8415870B2 (en) * | 2008-08-28 | 2013-04-09 | Panasonic Corporation | Semiconductor light emitting device and backlight source, backlight source system, display device and electronic device using the same |
| US9204518B2 (en) * | 2008-10-30 | 2015-12-01 | The Invention Science Fund I Llc | LED-based secondary general illumination lighting color slaved to alternate general illumination lighting |
| US8193713B2 (en) | 2008-10-30 | 2012-06-05 | The Invention Science Fund I, Llc | Apparatus and a method comprising illumination lighting fixture and sensor |
| US20100214282A1 (en) | 2009-02-24 | 2010-08-26 | Dolby Laboratories Licensing Corporation | Apparatus for providing light source modulation in dual modulator displays |
| US8921876B2 (en) * | 2009-06-02 | 2014-12-30 | Cree, Inc. | Lighting devices with discrete lumiphor-bearing regions within or on a surface of remote elements |
| US9293667B2 (en) | 2010-08-19 | 2016-03-22 | Soraa, Inc. | System and method for selected pump LEDs with multiple phosphors |
| EP2480816A1 (en) | 2009-09-25 | 2012-08-01 | Cree, Inc. | Lighting device with low glare and high light level uniformity |
| US10147850B1 (en) * | 2010-02-03 | 2018-12-04 | Soraa, Inc. | System and method for providing color light sources in proximity to predetermined wavelength conversion structures |
| US9275979B2 (en) | 2010-03-03 | 2016-03-01 | Cree, Inc. | Enhanced color rendering index emitter through phosphor separation |
| BR112012032027A2 (en) | 2010-06-17 | 2016-11-08 | Koninkl Philips Electronics Nv | display and lighting arrangement, space, lighting device for use in a display and lighting arrangement and method of controlling the light provided to a person in pose |
| US8297767B2 (en) * | 2010-09-07 | 2012-10-30 | Xicato, Inc. | LED-based illumination modules with PTFE color converting surfaces |
| US11251164B2 (en) | 2011-02-16 | 2022-02-15 | Creeled, Inc. | Multi-layer conversion material for down conversion in solid state lighting |
| JP2013029548A (en) * | 2011-07-26 | 2013-02-07 | Dainippon Printing Co Ltd | Backlight and liquid crystal display device |
| WO2013028900A1 (en) | 2011-08-24 | 2013-02-28 | Dolby Laboratories Licensing Corporation | High dynamic range displays having wide color gamut and energy efficiency |
| KR20130105770A (en) * | 2012-03-15 | 2013-09-26 | 삼성디스플레이 주식회사 | Display apparatus including the same, and method of driving the display apparatus |
| RU2494495C1 (en) * | 2012-03-30 | 2013-09-27 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Санкт-Петербургский национальный исследовательский университет информационных технологий, механики и оптики" | Multielement colour radiation source |
| KR102066614B1 (en) * | 2013-02-28 | 2020-01-15 | 엘지이노텍 주식회사 | An illuminating apparatus |
| CN104241262B (en) | 2013-06-14 | 2020-11-06 | 惠州科锐半导体照明有限公司 | Light emitting device and display device |
| KR20160056386A (en) * | 2014-11-10 | 2016-05-20 | 삼성디스플레이 주식회사 | Display apparatus |
| DE102015100842A1 (en) * | 2015-01-21 | 2016-07-21 | Tailorlux Gmbh | Lighting device with a phosphor layer and different light emitting diodes |
| CN104793397B (en) * | 2015-03-16 | 2018-11-02 | 厦门天马微电子有限公司 | Liquid crystal display die set and liquid crystal display device |
| DE102015107739A1 (en) * | 2015-05-18 | 2016-11-24 | Osram Opto Semiconductors Gmbh | Light source with multiple semiconductor components |
| WO2017105173A1 (en) * | 2015-12-14 | 2017-06-22 | Oviedo Montaño Ruben Carlos | Led device and light reflection system |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE69331896T2 (en) | 1992-07-13 | 2002-09-26 | Seiko Epson Corp | WIDE LIGHTING DEVICE AND LIQUID CRYSTAL DISPLAY |
| JPH07176794A (en) | 1993-12-17 | 1995-07-14 | Nichia Chem Ind Ltd | Planar light source |
| KR100200663B1 (en) * | 1996-03-20 | 1999-06-15 | 손욱 | Back-light device for lcd |
| JPH11510968A (en) | 1996-06-11 | 1999-09-21 | フィリップス エレクトロニクス ネムローゼ フェンノートシャップ | Visible light emitting display including ultraviolet light emitting diode and ultraviolet excited visible light emitting phosphor and method of manufacturing the device |
| US5803579A (en) * | 1996-06-13 | 1998-09-08 | Gentex Corporation | Illuminator assembly incorporating light emitting diodes |
| DE59814117D1 (en) * | 1997-03-03 | 2007-12-20 | Philips Intellectual Property | WHITE LUMINESCENCE DIODE |
| JP3378465B2 (en) * | 1997-05-16 | 2003-02-17 | 株式会社東芝 | Light emitting device |
| US5813753A (en) * | 1997-05-27 | 1998-09-29 | Philips Electronics North America Corporation | UV/blue led-phosphor device with efficient conversion of UV/blues light to visible light |
| US6252254B1 (en) | 1998-02-06 | 2001-06-26 | General Electric Company | Light emitting device with phosphor composition |
| US6329676B1 (en) * | 1999-03-01 | 2001-12-11 | Toru Takayama | Flat panel solid state light source |
-
2001
- 2001-07-31 DE DE10137042A patent/DE10137042A1/en not_active Withdrawn
-
2002
- 2002-07-04 EP EP02015001A patent/EP1282171B1/en not_active Expired - Lifetime
- 2002-07-04 AT AT02015001T patent/ATE513313T1/en active
- 2002-07-19 US US10/199,932 patent/US6799865B2/en not_active Expired - Lifetime
- 2002-07-29 CA CA002396019A patent/CA2396019A1/en not_active Abandoned
- 2002-07-30 JP JP2002221344A patent/JP4035394B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP1282171B1 (en) | 2011-06-15 |
| US20030026096A1 (en) | 2003-02-06 |
| DE10137042A1 (en) | 2003-02-20 |
| EP1282171A3 (en) | 2010-06-09 |
| JP2003141905A (en) | 2003-05-16 |
| EP1282171A2 (en) | 2003-02-05 |
| ATE513313T1 (en) | 2011-07-15 |
| US6799865B2 (en) | 2004-10-05 |
| JP4035394B2 (en) | 2008-01-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6799865B2 (en) | LED-based planar light source | |
| KR100986359B1 (en) | Light emitting apparatus and display apparatus having the same | |
| EP1669429B1 (en) | Phosphor converted light-emitting device | |
| JP6151753B2 (en) | Light emitting device and display device including the same | |
| EP2074475B1 (en) | Illumination system and display device | |
| KR100771811B1 (en) | White light emitting device | |
| US8299701B2 (en) | Lighting device having illumination, backlighting and display applications | |
| CN109616011B (en) | Backlight module and display device | |
| US20070103931A1 (en) | Assembly device for a sidelight light source module and liquid crystal panel | |
| KR20060006727A (en) | Light emitting diode and backlight module having light emitting diode | |
| WO2014180053A1 (en) | Backlight module of display apparatus, and white-light led | |
| CN101834266A (en) | Light-emitting device, the light source module that is used for LCD backlight and LCD | |
| CN109799647A (en) | A kind of backlight and liquid crystal display die set | |
| KR20070054826A (en) | Light emitting diode package and driving method thereof | |
| JP3409666B2 (en) | Surface light emitting device and display device using the same | |
| JP2003249112A (en) | Planar light-emitting device and display device using the same | |
| JP2002270020A (en) | Light source device | |
| KR100780186B1 (en) | Backlight unit for LCD using light emitting diode | |
| KR20060112453A (en) | Photo-luminescenct liquid crystal display | |
| KR20050093047A (en) | Backlight unit | |
| US7737635B2 (en) | High efficiency white light emitting diode and method for manufacturing the same | |
| KR20110096923A (en) | White light emitting diode light source | |
| CN100383990C (en) | Light device | |
| JP2008299299A (en) | Liquid crystal display device and its backlight module and light emitting module | |
| KR101667791B1 (en) | Light emitting diode and liquid crystal display device including the same |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued | ||
| FZDE | Discontinued |
Effective date: 20080729 |